A conventional technique of preparing, as a subject of analysis, a sample obtained by crystallizing biological macromolecules such as proteins, and analyzing and evaluating the sample using X-ray crystal structural analysis and NMR methods exists as a technique for analyzing the three-dimensional structure of molecules. This technique, however, requires crystallization of the sample, and cannot be applied to analysis of samples such as membrane proteins that are difficult to crystallize.
Single particle structural analysis has been proposed as a technique which requires no crystallization of the sample in which a structure of proteins is analyzed using a Cryo-Transmission Electron Microscope (TEM) (see Non-Patent Documents 1 and 2). Single particle structural analysis is a method for extracting sample images each representing a globular protein from a TEM image that is obtained from a globular protein sample cooled at a cryogenic temperature by a transmission electron microscope (TEM), and determining the three-dimensional structure of the globular protein sample based on the sample images. This technique reduces noise in the sample images by taking the average of the sample images.
One case of analyzing the three-dimensional structure of molecules is described above. Typically, image processing can be used for structural analysis of the subject of analysis.    Non-Patent Document 1: Sato Chikara, et al., “Protein Structural analysis not Using Crystal by Single Particle Analysis: Case of Structure of Voltage Dependent Na+ Channel”, Electron Microscope, 2002, Volume 37, No. 1, pp. 40 to 44.    Non-Patent Document 2: J. Frank, “Three-Dimensional Electron Microscopy of Macromolecular Assemblies”, Oxford University Press, 2006, p. 122 and 193 to 276.